This program concerns the genetics, biology and virology of cancer. New major developments in our understanding of the mechanisms of malignant transformation have resulted from the investigations carried out at The Wistar Institute. The role of specific oncogenes in the pathogenesis of leukemias and lymphomas in man has been assessed and the mechanisms of their activation have been determined. In addition, very recently it has been possible to establish that the gene for the alpha chain of the T cell receptor may have an important role in oncogene activation in human T cell leukemia. New oncogenes involved in hematopoietic malignancies have been identified, cloned and characterized. In addition new breakthroughs have been achieved in the area of nuclear transfer into fertilized eggs. The extremely high rate of success in this type of experiment opens new avenues in our ability to understand mammalian development and to investigate the role of cytoplasmic nuclear factors during early embryogenesis.